A heater used, for example, in a glow plug of an automobile engine includes a heating element, leads bonded to respective end portions of the heating element, and an insulating base in which the heating element and the leads are embedded. In addition, a compound of various metals is added as an additive to the heating element. The additive serves as an adjustment component for changing a temperature coefficient of resistance (for example, see Japanese Unexamined Patent Application Publication No. 2000-156275).
In recent years, there is a tendency that exhaust gas regulation and fuel efficiency regulation on diesel engine have been strengthened every year, and high temperature and high pressure at the time of combustion is required. Accordingly, the glow plug used at high temperatures is also progressed.
Here, the compound of various metals added as an adjustment component to the heating element diffuses into the insulating base side at the time of firing. In addition, when used at high temperatures, the compound diffused into the insulating base is ionized and transferred to the heating element of the cathode side, and therefore, there is a problem in that a resistance value of the heating element changes.
The present invention has been developed in light of the above circumstances, and an object thereof is to provide a heater, capable of suppressing the change in the resistance value of the heating element even when being used at a high temperature and having high reliability, and a glow plug with the same.